Production of nitriles



3,055,738 PRODUCTION OF NITRILES Lawrence J. Krebaurn, Texas City, Tex., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation atet percentage basis. Yields calculated from the analytical data under the various conditions are recorded in Table I. It should be noted that all yield values were calculated upon the basis that one half of the cyanogen produced came from acetonitrile. If it had been assumed that lf fifi fi ff Filed Oct 24, 1960, Sen 64,301 5 cyanogen was produced totally from HCN, the calculated 6 Claims (C] 23 151) ylelds of malononitrile, for example, would have been higher. Likewise, the method of analysls used for ma- The present invention relates to a new method of prelononitrile tended to give low values because of the paring certain organic nitriles from acetonitrile and hynon-volatility of this compound. Hence, all yields given drogen cyanide (HON). are conservative.

Table l Yields Based on AeN (percent) Reaction AcN 1 Run Temp, Time Mole Ratio, Conv. N0. O. (See) HONzAcN l percent Malono- Acrylo- Fumaro- Propar- Oyano- 4 nitrile nitrile nitrile g gen Nitrite 800 1. 77 1. 6:1 1.8 19.1 35. 3 0. 0 0. 0 8.8 850 1. 34 1. 7:1 8. s 19. 0 as. s 11.0 0. 0 7. 7 905 0.18 4.011 22.1 9.6 6.5 6.1 8.0 10.5 950 0.16 4.911 43. 7 10. 5 11.2 3. 5 18.8 24. 5 1, 000 0.11 4. 6:1 53.6 2. 9 11. s 2.1 21.8 23. s 1, 045 0. 08 6. 3:1 55.6 0. 4 11. 4 2. 6 17.8 22. 4

1 Acetonitrile.

According to the invention, acetonitrile and HCN are 'It will be seen from the foregoing data that the proporreacted at a temperature in the range from about 700 C. tion of the various products in the reaction mixture proto about 1100 C. to produce a reaction mixture conduced by reaction of acetonitrile and HON can be varied taining at least one of the compounds chosen from the by varying the reaction conditions. Generally speaking, group consisting of malononitrile, acrylonitrile, fumarothose temperatures at the higher end of the temperature nitrile, propargyl nitrile and cyanogen. In the preferred range tend to produce propargyl nitrile and cyanogen in embodiment of the process, a gaseous mixture of acetopredominating proportions over malononitrile and acrylonitrile and HCN together with a diluent gas if one is denitrile while with those at the lower end of the temperasired is continuously passed through a reaction zone heated ture range, malononitrile and acrylonitrile predominate in to reaction temperature at a rate such that the mixture the reaction product. remains therein for the desired reaction period. The gases Variations in procedure and reaction conditions from issuing from the reaction zone are quenched as rapidly as those given in the example may be made without departpossible and the different nitriles are recovered by coning from the scope of the invention. For example, the ventional condensation and fiactional distillation techreaction may be carried out in a tubular reactor of quartz, niques. porcelain or any other refractory material which is non- The invention is illustrated in the following example catalytic and capable of withstanding the temperatures which, however, is not to be construed as limiting it in employed as well as in the silica reactor exemplified. The any manner whatsoever. reactant gases can, if desired, be passed through a series of reaction zones heated to.reaction temperature, the mix- EXAMPLE I ture being cooled as it issues from each reactor to re- The experimental apparatus was comprised of a recover the desired reaction products therefrom. Unreacted actor consisting of empty Vycor (96% silica) tube havfeed materials can then be recycled. ing an effective length of 20 cm. disposed Within a mufile While the lowest temperature exemplified is 800 C., furnace together with inlet and outlet manifolds, vaporthe reaction can be efiected at temperatures as low as izers for the HCN and acetonitrile with the required ac- 700 C. Operation at this low temperature, however, is cessory lines, a mixing chamber for the reactant gases, 59 impractical because of the low conversions obtained. The ad a product gas receiver. Prior to the run, the system practical upper temperature limit for the reaction is 1100 was warmed up while argon was passed through it. C. As indicated previously, the preferred temperatures Acetonitnle and HCN vapors were fed through rotameters within the broad reaction temperature range of 700 C. into the mixing chamber and then passed through the to 1100 C. will depend to a great extent upon the distrireactor which had been heated to the desired temperature. bution desired in the reaction product. The preferred The effluent gas from the reactor was collected in a temperatures for the preparation of malononitrile and heated receiver from which it was exhausted into a acrylonitrile, for example, lie in the range from about sample bomb. Reaction times in the reactor were varied 700 C. to about 900 C. while the preferred temperatures by using tubes of various diameters, by changing feed for producing cyanogen and propargyl nitrile are those rate, or by adding an inert diluent such as argon to the 60 from about 900 C. to about 1100 C. The amount of reaction mixture. A series of runs was made following fumaronitrile produced in general decreases as the temthis procedure under various conditions of temperature, perature of the reaction increases but does not vary so reactant feed ratios, reaction time, etc. Gas samples sharply as do the other nitrile products. were obtained and analyezd by means of a mass spectrom- Reaction time, i.e., the time during which the reaction eter. To obtain realistic values for the higher boiling mixture is maintained in the reaction zone, varies with products, the sample bomb and the spectrometer inlet system were heated. Analyses were expressed on a mole the particular temperature employed. Generally, a decrease in temperature requires an increase in reaction time and conversely, an increase in temperature will necessitate a shorter reaction time. Reaction times from about 0.01 seconds to about seconds can be satisfactorily employed over the broad temperature range from 700 C. to 1100 C. In the preferred temperature range for producing malononitrile and acrylonitrile, reaction times may vary preferably from about 3 seconds at 700 C. to about 0.2 seconds at 900 C. In the preferred temperature range for producing propargyl nitrile and cyanogen, reaction times may vary from about 1 second at 900 C. to about 0.1 second at 1100 C.

The pressure employed is preferably atmospheric but operation at either subatmospheric or superatmospheric pressure is feasible.

A wide range of reactant ratios can be employed. Mole ratios of HCN to acetonitrile from 1:1 on up to :1 can be employed. Preferred, however, for practical operation are those in the range from 3:1 to 5:1.

"Inert gaseous diluents can be present in the reaction mixture if desired and gases such as nitrogen, argon and the like may be employed. HCN can be employed in excess as a practical diluent as well 'as a reactant. The proportions of inert diluent would be limited only by practical considerations.

Recovery of the various nitrile products can be effected by low temperature condensation of the effluent gas mixtures followed by fractional distillation of the liquid condensate in a conventional manner. Unreacted acetonitrile and HON can be recycled to the reaction zone if desired.

What is claimed is:

1. The process of reacting acetonitrile and hydrogen cyanide at 'a temperature within the range from about 700 C. to about 1100 C. to produce at least one of the organic nitriles of the group consisting of malononitrile, acrylonitrile, fumaronitrile, propargyl nitrile, and cyanogen.

2. A method for the preparation of malononitrile which comprises reacting acetonitrile with hydrogen cyanide at a temperature in the range from about 700 C. to about 900 C.

3. A method for the preparation of acrylonitrile which comprises reacting acetonitrile with hydrogen cyanide at a temperature in the range from about 700 C. to about 900 C.

4. A method for the preparation of propargyl nitrile which comprises reacting 'acetonitrile with hydrogen cyanide at a temperature in the range from about 900 C. to about 1100 C.

5. A method for the preparation of cyanogen which comprises reacting acetonitrile with hydrogen cyanide at a temperature in the range from about 700 C. to about 1100 C.

6. A method for the preparation of fumaronitrile which comprises reacting acetonitrile with hydrogen cyanide at a temperature in the range from about 850 C. to about 1100 C.

No references cited. 

1. THE PROCESS OF REACTING ACETONITRILE AND HYDROGEN CYANIDE AT A TEMPERATURE WITHIN THE RANGE FROM ABOUT 700* C. TO ABOUT 1100* C. TO PRODUCE AT LEAST ONE OF THE ORGANIC NITRILES OF THE GROUP CONSISTING OF MALONONITRILE, ACRYLONITRILE, FUMARONITRILE, PROPARYGL NITRILE, AND CYANOGEN. 